Giuliani and the firm, Greenberg Traurig, released a joint statement on Thursday saying that the resignation was effective a day earlier. Giuliani took a leave of absence from the firm in April to represent Trump, but, he said, “the pressing demands” of special counsel Robert Mueller’s Russia investigation led him to decide to permanently resign.

“This way, my sole concentration can be on this critically important matter for our country,” Giuliani said in a statement.

He added: “I will always treasure the personal friendships I have made with everyone at Greenberg Traurig.”

Richard A. Rosenbaum, the firm’s chairman, said Giuliani had planned “to play a limited role, for a short period of time, to address specific matters for President Trump.”

“After recognizing that this work is all consuming and is lasting longer than initially anticipated, Rudy has determined it is best for him to resign from the firm, effective May 9th,” Rosenbaum said in the statement.

Giuliani’s abrupt and immediate departure from the firm comes after a series of media appearances in which he discussed, among other things, Michael Cohen’s payment of $130,000 to adult film star Stormy Daniels.

Cohen, another personal lawyer to the president, admitted in February to making the payment, but denied Trump knew about it. Giuliani, however, told Fox News that Trump not only knew about the payment, but reimbursed Cohen. Giuliani later backpedaled after Trump said Giuliani didn’t have “his facts straight.”

Giuliani also suggested that payments like Cohen’s to Daniels ― aimed at ensuring her silence about an alleged Trump affair ― are common practice at his firm.

“That was money that was paid by his lawyer, the way I would do, out of his law firm funds,” he said. “Michael would take care of things like this like I take care of this with my clients.”

“We cannot speak for Mr. Giuliani with respect to what was intended by his remarks,” a Greenberg Traurig spokeswoman told the Times on Thursday. “Speaking for ourselves, we would not condone payments of the nature alleged to have been made or otherwise without the knowledge and direction of a client.”